A 4-year-old girl died late this afternoon, two days after she, her 9-year-old brother and her mother were injured in a fire set by the children's father that also claimed his life and her mother's, authorities said.

The girl, identified as Neriyah Beller, of the 4500 block of West Harrison Street, was declared dead at 4:49 p.m., according to the Cook County medical examiner's office.

Earlier, the girl's grandmother, mother of Nathaniel Beler, suspected of pouring a flammable liquid on several people, setting off the fatal fire early Saturday in the 4200 block of West 21st Place, asked for prayers for Neriyah and her brother. Some public records also give the family's name as Beller, and it was reported to authorities including the medical examiner's office as Beller, officials said.

"I pray for the Johnson family," said Willie Beler, 52, at a news conference in front of her Lawndale home. "And I ask the media to pray for the Beler and Johnson family and just please keep my grandchildren uplifted."

Nathaniel Beler, 29, was suspected of setting the fire in a home that left Taniya Johnson, 33, dead, and injured the couple's two children, officials said. Nathaniel Beler himself was declared dead midday Sunday at Stroger Hospital.

Johnson died from thermal injuries from the fire and sharp force injuries in a homicide, the medical examiner's office determined Sunday. She had been declared dead on Saturday, the day of the blaze.

The boy remained in very critical condition this evening in the pediatric intensive care unit, according to Stroger hospital spokeswoman Marisa Kollias.

Willie Beler said Johnson and her grandchildren were visiting her home when the fire occurred.

The family had enjoyed a homemade meal of hamburgers and French fries before the kids, Johnson and Nathaniel Beler retired to his bedroom, Willie Beler said. But around 4 a.m., Beler said she was standing in her bedroom doorway when she saw her son walk past on fire.

Authorities said the fire was being investigated as an arson and it appeared it started after someone poured an accelerant around the apartment and possibly on the children.

In 2007, Beler pleaded guilty to misdemeanor domestic battery against Johnson, and had an order of protection entered against him according to court records.

"They had issues," Beler said of their relationship. "They were trying to work things out and get themselves together."

Beler said the two had been engaged for about two years.

"They both loved their kids. They would do anything for their kids," she said.

Beler said her son had been living with her the past few months. He was taking medication for bipolar disorder after being diagnosed in 2011, she said.